1. Field
The present disclosure relates to a colorimetric detection sensor and a colorimetric detection method of a cyanide anion (CN−) based on etching of gold nanorods.
More particularly, the present disclosure relates to a colorimetric detection sensor and a colorimetric detection method, which use label-free nanorods having no modifier attached to the surface of gold nanorods (AuNRs), wherein the aspect ratio of nanorods, pH condition and/or amount of a surfactant are controlled to carry out selective etching and to cause a change in color only by CN− so that CN− contained or dissolved in poison samples, water-contaminated environmental samples and legal evidence samples may be detected with ease, and show excellent selectivity, sensitivity and quantitative analyzability to CN− to provide high usefulness.
Description about National Support Research and Development
This study is conducted by the support of Ministry of Science, ICT and Future Planning, and the subject title is Development of Efficient and Cutting-Edge Analysis Technique and Establishment of On-site Evidence Predictive Factor Data Base (Subject Identification No.: 1711018287).
2. Description of the Related Art
Many cyanide compounds are toxic, because CN− functions as a reaction inhibitor against cytochrome C oxidase that is an enzyme present in an electron transfer chain in cellular mitochondria. When CN− is bound with the enzyme, electron transfer from cytochrome C to oxygen is interrupted. As a result, the electron transfer chain is broken and the cell cannot produce ATP any more for energy. The most harmful cyanide compound is an inhalable hydrogen cyanide that exists in a gaseous state at room temperature. Human who eats a solid cyanide compound or cyanide solution in a small amount of 200 mg or inhales 270 ppm of cyanide gas may be dead within 1 minute.
Various detection methods and criteria have been suggested for CN− in an environmental sample, food or drinking water. The criterion for drinking water is 200 ppb according to EPA of USA and that of Europe is 50 ppb. In addition, the criterion for mineral water is 70 ppb or less. There have been suggested some official methods for analyzing CN−, including titration and spectrometry [US EPA, Titrimetric and manual spectrophotometric determinative methods for cyanide, Method 9014, 1996], potentiometric titration using a cyanide-selective electrode [US EPA, Potentiometric determination of cyanide in aqueous samples and distillates with ion-selective electrode, Method 9213, 1996], flow injection (FI)-amperometry [US EPA, Available cyanide by flow injection, ligand exchange and amperometry, Method OIA-1677, 2004], or the like.
Gold nanorods (AuNRs) are obtained by reducing chlorauric acid hydrate (HAuCl4.H2O) with NaBH4 in the presence of cetyltrimethyl ammonium bromide (CTAB) to provide gold nanoparticles and carrying out further reduction with ascorbic acid. Such nanorods have been applied widely in various industrial fields, including sensors, depending on their sizes and shapes.
Nanoparticle colorimetric sensor analysis using a surface plasmon resonance phenomenon of gold nanoparticles theoretically utilizes the principle of inducing free electron vibration of the surface of nanoparticles by the light waves absorbed thereto. Herein, a resonance phenomenon occurs to emit a specific wavelength and shows various colors depending on size, shape and type of the particles. Since gold nanorods (AuNRs) may have a variable color according to a change in dimension of width and length, they may be applied widely to sensors for determining and monitoring a specific material which etchs the nanorods (Chem Soc. Rev. 2013, 42, 2679-2724).
As a metal ion detection colorimetric sensor using gold nanorods known to date, Professor Jiaming Ryu (Jangchow Nomal University, China) has developed a sensor for detecting hexavalent chromium ion (Cr6+) by using Cr (VI) ions which can etch gold nanorods selectively [Sensors and Actuators B, 2011, 155, 817-822]. In addition, selective detection of Cu2+ ions has been disclosed wherein it uses a change in maximum peak wavelength of UV-Vis spectrum when poly(sodium-4-styrene sulfonate) and polyethylene imine (PEI) are adsorbed to gold nanorods and then bound with Cu2+ ions [J. of Colloid and Interface Science 439 (2015) 7-11]. Further, Professor Andres D. Campiglia of Central Florida University, USA has suggested a sensor for analyzing mercury by binding (3-mercaptopropyl)trimethoxysilane to gold nanorods [Talanta 99 (2012) 180-185].
According to the inventors' observations, there is a need for a sensor technology for carrying out rapid detection and analysis of CN− in environmentally contaminated samples, forensic science samples, drinking water, medicine or industrial sites where chemicals are treated, etc., which may allow real time determination and continuous management, have high stability and enable downsizing.